fix(db): move db constants to other file to avoid circular ref (#1858)

* fix(db): move db constants to other file to avoid circular ref

lib/db.js referenced lib/operations/db_ops.js, which in turn
referenced lib/db.js to get some constants. Moved constants to
their own file, and used dynamic imports to get DB constructor

Fixes NODE-1692

lib/constants.js

@@ -0,0 +1,10 @@
+'use strict';
+
+module.exports = {
+  SYSTEM_NAMESPACE_COLLECTION: 'system.namespaces',
+  SYSTEM_INDEX_COLLECTION: 'system.indexes',
+  SYSTEM_PROFILE_COLLECTION: 'system.profile',
+  SYSTEM_USER_COLLECTION: 'system.users',
+  SYSTEM_COMMAND_COLLECTION: '$cmd',
+  SYSTEM_JS_COLLECTION: 'system.js'
+};

lib/db.js

@@ -19,6 +19,7 @@ const resolveReadPreference = require('./utils').resolveReadPreference;
 const ChangeStream = require('./change_stream');
 const deprecate = require('util').deprecate;
 const deprecateOptions = require('./utils').deprecateOptions;
+const CONSTANTS = require('./constants');
 
 // Operations
 const addUser = require('./operations/db_ops').addUser;
@@ -532,7 +533,7 @@ Db.prototype.listCollections = function(filter, options) {
   // Return options
   const _options = { transforms: listCollectionsTransforms(this.s.databaseName) };
   // Get the cursor
-  cursor = this.collection(Db.SYSTEM_NAMESPACE_COLLECTION).find(filter, _options);
+  cursor = this.collection(CONSTANTS.SYSTEM_NAMESPACE_COLLECTION).find(filter, _options);
   // Do we have a readPreference, apply it
   if (options.readPreference) cursor.setReadPreference(options.readPreference);
   // Set the passed in batch size if one was provided
@@ -974,11 +975,11 @@ Db.prototype.getLogger = function() {
  */
 
 // Constants
-Db.SYSTEM_NAMESPACE_COLLECTION = 'system.namespaces';
-Db.SYSTEM_INDEX_COLLECTION = 'system.indexes';
-Db.SYSTEM_PROFILE_COLLECTION = 'system.profile';
-Db.SYSTEM_USER_COLLECTION = 'system.users';
-Db.SYSTEM_COMMAND_COLLECTION = '$cmd';
-Db.SYSTEM_JS_COLLECTION = 'system.js';
+Db.SYSTEM_NAMESPACE_COLLECTION = CONSTANTS.SYSTEM_NAMESPACE_COLLECTION;
+Db.SYSTEM_INDEX_COLLECTION = CONSTANTS.SYSTEM_INDEX_COLLECTION;
+Db.SYSTEM_PROFILE_COLLECTION = CONSTANTS.SYSTEM_PROFILE_COLLECTION;
+Db.SYSTEM_USER_COLLECTION = CONSTANTS.SYSTEM_USER_COLLECTION;
+Db.SYSTEM_COMMAND_COLLECTION = CONSTANTS.SYSTEM_COMMAND_COLLECTION;
+Db.SYSTEM_JS_COLLECTION = CONSTANTS.SYSTEM_JS_COLLECTION;
 
 module.exports = Db;

lib/operations/db_ops.js

@@ -4,13 +4,13 @@ const applyWriteConcern = require('../utils').applyWriteConcern;
 const Code = require('mongodb-core').BSON.Code;
 const resolveReadPreference = require('../utils').resolveReadPreference;
 const crypto = require('crypto');
-const Db = require('../db');
 const debugOptions = require('../utils').debugOptions;
 const handleCallback = require('../utils').handleCallback;
 const MongoError = require('mongodb-core').MongoError;
 const parseIndexOptions = require('../utils').parseIndexOptions;
 const ReadPreference = require('mongodb-core').ReadPreference;
 const toError = require('../utils').toError;
+const CONSTANTS = require('../constants');
 
 const count = require('./collection_ops').count;
 const findOne = require('./collection_ops').findOne;
@@ -64,6 +64,8 @@ const illegalCommandFields = [
  * @param {Db~resultCallback} [callback] The command result callback
  */
 function addUser(db, username, password, options, callback) {
+  const Db = require('../db');
+
   // Did the user destroy the topology
   if (db.serverConfig && db.serverConfig.isDestroyed())
     return callback(new MongoError('topology was destroyed'));
@@ -83,7 +85,7 @@ function addUser(db, username, password, options, callback) {
       const db = options.dbName ? new Db(options.dbName, db.s.topology, db.s.options) : db;
 
       // Fetch a user collection
-      const collection = db.collection(Db.SYSTEM_USER_COLLECTION);
+      const collection = db.collection(CONSTANTS.SYSTEM_USER_COLLECTION);
 
       // Check if we are inserting the first user
       count(collection, {}, finalOptions, (err, count) => {
@@ -296,7 +298,7 @@ function createIndex(db, name, fieldOrSpec, options, callback) {
     finalOptions.checkKeys = false;
     // Insert document
     db.s.topology.insert(
-      `${db.s.databaseName}.${Db.SYSTEM_INDEX_COLLECTION}`,
+      `${db.s.databaseName}.${CONSTANTS.SYSTEM_INDEX_COLLECTION}`,
       doc,
       finalOptions,
       (err, result) => {
@@ -630,6 +632,8 @@ function profilingLevel(db, options, callback) {
  * @param {Db~resultCallback} [callback] The command result callback
  */
 function removeUser(db, username, options, callback) {
+  const Db = require('../db');
+
   // Attempt to execute command
   executeAuthRemoveUserCommand(db, username, options, (err, result) => {
     if (err && err.code === -5000) {
@@ -638,7 +642,7 @@ function removeUser(db, username, options, callback) {
       const db = options.dbName ? new Db(options.dbName, db.s.topology, db.s.options) : db;
 
       // Fetch a user collection
-      const collection = db.collection(Db.SYSTEM_USER_COLLECTION);
+      const collection = db.collection(CONSTANTS.SYSTEM_USER_COLLECTION);
 
       // Locate the user
       findOne(collection, { user: username }, finalOptions, (err, user) => {

test/unit/create_index_error_tests.js

@@ -0,0 +1,57 @@
+'use strict';
+
+const expect = require('chai').expect;
+const mock = require('mongodb-mock-server');
+
+describe('CreateIndexError', function() {
+  const test = {};
+  beforeEach(() => mock.createServer().then(_server => (test.server = _server)));
+  afterEach(() => mock.cleanup());
+
+  it('should error when createIndex fails', function(done) {
+    const ERROR_RESPONSE = {
+      ok: 0,
+      errmsg:
+        'WiredTigerIndex::insert: key too large to index, failing  1470 { : "56f37cb8e4b089e98d52ab0e", : "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa..." }',
+      code: 17280
+    };
+
+    test.server.setMessageHandler(request => {
+      const doc = request.document;
+
+      if (doc.ismaster) {
+        return request.reply(Object.assign({}, mock.DEFAULT_ISMASTER));
+      }
+
+      if (doc.createIndexes) {
+        return request.reply(ERROR_RESPONSE);
+      }
+
+      if (doc.insert === 'system.indexes') {
+        return request.reply(ERROR_RESPONSE);
+      }
+    });
+
+    const client = this.configuration.newClient(`mongodb://${test.server.uri()}`);
+
+    const close = e => client.close().then(() => done(e));
+
+    client
+      .connect()
+      .then(() => client.db('foo').collection('bar'))
+      .then(coll => coll.createIndex({ a: 1 }))
+      .then(
+        () => close('Expected createIndex to fail, but it succeeded'),
+        e => {
+          try {
+            expect(e).to.have.property('ok', ERROR_RESPONSE.ok);
+            expect(e).to.have.property('errmsg', ERROR_RESPONSE.errmsg);
+            expect(e).to.have.property('code', ERROR_RESPONSE.code);
+            close();
+          } catch (err) {
+            close(err);
+          }
+        }
+      );
+  });
+});